Hicklin Lake (also known as Hicks or Garrett) was monitored by volunteers in 1996 through 1998. The data indicated that the lake was highly productive (eutrophic), with fair to poor water quality. Recurring bluegreen blooms have frequently limited beneficial uses of the lake, situated in Lakewood Park. Hicklin Lake was placed on the EPA 303d list of impaired water bodies for both phosphorus and fecal coliform concentrations, although it was reclassified to category 2 in 2008 for fecal coliform bacteria.
A baseline water quality study was completed in 2004, and alum treatments have been carried out to reduce phosphorus in 2005 and again in 2011 by the King County Lake Stewardship Program. Both treatments were successful, with summer monitoring following the condition of the lake to measure effectiveness. Further treatments may be necessary in the future, although improvements in the stormwater facilities and best management practices are ongoing in the watershed.
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The average of these three TSI indicators during the growing season can be used to place lakes in one of three broad categories: <40 = oligotrophic (low productivity), 40 to 50 = mesotrophic (moderate productivity) >50 = eutrophic (highly productive).
